1. Field of the Invention
The present invention relates to semiconductor devices and their manufacture, and more specifically to a structure and method of making a semiconductor chip having a trench capacitor.
2. Description of the Related Art
Semiconductor chips are flat thin bodies which have active semiconductor devices, e.g., transistors, formed within a thin active semiconductor region adjacent a major surface of the chip. Certain kinds of semiconductor chips, such as those which incorporate dynamic random access memories (“DRAMs”), include capacitors which are connected with active semiconductor devices to perform electrical functions of the chip. The on-chip capacitors can be trench capacitors which extend in a downward direction below the chip's active semiconductor region. Another type of on-chip capacitors are stack capacitors which are formed in one or more layers disposed above the active semiconductor region. In either case, the particular way the capacitors are provided on the chip can affect the amount of capacitance provided by each capacitor, as well as affect the amount of area of the active semiconductor region that remains available to form the active semiconductor devices.
One of the challenges of fabricating on-chip capacitors is to obtain sufficient capacitance while limiting the amount of area of the active semiconductor device region taken up by the capacitors. Further improvements can be made in the structure and fabrication of on-chip trench capacitors for achieving these or other goals.